Sir William Stewart, who chaired the inquiry, told BBC Radio 4's Today programme he would not allow his own grandchildren to use mobiles on a regular basis.

He said: "The reason we don't recommend long-term use of mobile phones by children is that their skulls are not fully fixed, their nervous system is not fully developed and as youngsters, they are likely to be exposed longer during their lifetimes to mobile phone radiation.

"In many cases they are frequent users."

But the task force is concerned that not enough research has been done.

Radiation tests

With most people now using mobiles - many of them children - the task force has commissioned a £7.4m research programme designed to decide whether mobiles pose a risk.

The studies will examine effects on behaviour, blood pressure and hearing.

They will also test whether mobile radiation increases the risks of cancers and whether using mobiles affect the performance of drivers, he says.

Minister for Public Health Yvette Cooper welcomed the research programme announcement.

She said: "This package of research projects will make the UK a world leader in determining whether there are health effects from using mobile phones.

I started getting some quite bizarre health problems - starting off with short-term memory problems and eventually ending in a chronic tiredness - a sort of M.E.

Jim Mochanz, former mobile phone company employee

"We need to fill the gaps in our scientific knowledge as soon as possible so that we can provide people with the evidence they need to make an informed choice about using their mobile phones."

Critics say the research is too little too late to rapidly assess the long term safety of mobile phone use.

Jim Mochanz, who worked for 10 years installing mobile phone masts, told BBC Radio 4's Today programme he now suffers from memory loss and mood swings.

"I started getting some quite bizarre health problems - starting off with short-term memory problems and eventually ending in a chronic tiredness - a sort of M.E.," he said.

His colleagues had suffered "infinitely worse" problems which in some cases had been fatal, he added.

He said he was "bitterly disappointed" the research had not been undertaken earlier.

Last year a BBC investigation revealed that mobile phone retailers were failing to give proper advice about possible health risks to children.

A government leaflet issued last year advising customers about possible dangers was not available in three-quarters of the shops visited by BBC Radio Five Live reporters.